1. Field of the Invention
The present invention relates to an obstacle detecting system for detecting an object ahead of a moving body in the direction of movement of the moving body. The object is detected by an object detecting means such as a radar device provided on the moving body. The possibility of collision of the moving body with the object is determined, based on the result of the detection.
2. Description of the Prior Art
An obstacle detecting system is conventionally known from Japanese Patent Application Laid-open No. 11-23705, which is designed, so that an obstacle ahead of a vehicle is detected by a radar device which comprises an electromagnetic wave transmitting means for transmitting electromagnetic waves comprising laser beams or millimeter waves, ahead of the vehicle, and an electromagnetic wave receiving means for receiving the reflected waves resulting from the reflection of the electromagnetic waves from the object. When there is a possibility of a collision of the vehicle with the obstacle, a warning is provided to a driver, or automatic braking is carried out.
In such an obstacle detecting system, it is necessary to detect the obstacle in a detection area within a range of predetermined angles ahead of the vehicle and for this reason, the detection area is scanned laterally and longitudinally by the electromagnetic waves transmitted from the electromagnetic wave transmitting means of the radar device. Therefore, the obstacle is detected intermittently at intervals, wherein the interval period corresponds to a time taken for scanning the entire detection area one time by the electromagnetic wave.
To prevent the execution of the warning and the execution of the automatic braking which are not necessarily required for avoiding the collision, thereby reducing the sense of incompatibility provided to the driver, the following problem is encountered: It is necessary to detect the obstacle at an interval or period as short as possible to determine the presence or absence of the possibility of collision accurately, but a radar device having a short detection period is increased in size and is expensive.
The present invention has been accomplished with the above circumstance in view, and it is an object of the present invention to enhance the accuracy of determination of the possibility of a collision of the vehicle with the object, without shortening the interval or period for detection of the object by the object detecting means.
To achieve the above object, there is provided an obstacle detecting system comprising an object detecting means for detecting an object present in the direction of movement of a moving body, a speed detecting means for detecting the speed of movement of the moving body, and a collision-possibility determining means for determining a possibility of collision of the moving body with the object, based on the result of the detection by the object detecting means and the result of the detection by the speed detecting means. The determination period for determination of the possibility of collision by the collision-possibility determining means, is set to be shorter than the detection period for the detection of the object by the object detecting means.
With the above arrangement, the determination period for determination of the possibility of a collision by the collision-possibility determining means is set to be shorter than the detection period for detection of the object by the object detecting means. Therefore, it is possible to carry out the determination of the possibility of a collision at the short determination period without the use of a large-size and expensive object detecting means having a short detection period, thereby enhancing the determination accuracy.
In addition, the collision-possibility determining means detects the position of the object relative to the moving body based on the detection by the object detecting means and the detection by the speed detecting means to determine the possibility of collision based on the change in relative position. The relative position is detected at a period shorter than the detection period for the detection of the object by the object detecting means.
With the above arrangement, the change in position of the object relative to the moving body, is detected at a period shorter than the detection period for detection of the object by the object detecting means, and hence, the collision-possibility determining means can determine the possibility of collision accurately, based on the change in relative position.
Further, the determination period for the determination of the possibility of collision by the collision-possibility determining means becomes shorter, as the distance between the moving body and the object becomes shorter.
With the above arrangement, the determination period for the determination of the possibility of collision becomes shorter, as the distance between the moving body and the object becomes less. Therefore, when there is a high possibility of collision, the determination period can be shortened to enhance the determination accuracy.
The determination period for the determination of the possibility of collision by the collision-possibility determining means is shorter, as the relative speed between the moving body and the object becomes higher.
With the above arrangement, the determination period for the determination of the possibility of collision by the collision-possibility determining means becomes shorter, as the relative speed between the moving body and the object becomes higher. Therefore, when there is a high possibility of collision, the determination period can be shortened to enhance the determination accuracy.
The determination period for the determination of the possibility of collision by the collision-possibility determining means becomes shorter, as the lateral relative position of the object becomes closer to the moving body.
With the above arrangement, the determination period for the determination of the possibility of collision by the collision-possibility determining means becomes shorter, as the lateral relative position of the object becomes closer to the moving body. Therefore, when there is a high possibility of collision, the determination period can be shortened to enhance the determination accuracy.